Control of strip



United States Patent 3,421,708 CONTROL OF STRIP George GallowayNicholson, Ronald Jackman and Derek Stubbias, Sheilield, England,assignors to Davy and United Engineering Company Limited, Sheflield,

England Filed Sept. 26, 1966, Ser. No. 582,094

US. Cl. 242-57 4 Cl Int. Cl. B6511 25/04 ABSTRACT OF THE DISCLOSURE Whendrawing strip material from a coil on a pay-01f device by drive means itis desirable that the end of the coil be drawn oil? of the pay-offdevice at a very low speed and as it is also desirable for the remainderof the coil to be drawn off of the pay-oif device at as high a speed aspossible, it is necessary to initiate deceleration of the drive means ata particular instant of time which will cause the drive means to bedecelerated to zero just as the end of the coil is leaving the pay-ofidevice. It is diflicult for an operator to know at what moment toinitiate deceleration of' the drive means since the time at whichinitiation of the deceleration is started depends upon a number offeatures including the linear speed of withdrawal of the strip. Theinvention provides control means which automatically initiatedeceleration of the drive means so that at the end of the decelerationperiod the end of the strip material is at a predetermined positionrelative to the pay-ofi device.

This invention relates to the control of strip material drawn from acoil on a pay-01f device.

When strip material is drawn from a coil on a pay-oil device by drivingmeans, for example, a rolling mill, it is difiicult for an operator toknow at what moment to initiate deceleration of the driving means sincethe strip thickness and speed will vary from coil to coil.

In one aspect the invention provides apparatus for controlling stripmaterial, comprising a strip pay-off device associated with drivingmeans for drawing strip there from, comprising means for obtaining acontinuous signal proportional to the size of the coil on the pay-oftdevice, and means responsive to this signal for initiating decelerationof the drive means at a predetermined rate.

In another aspect the invention comprises apparatus for control of stripmaterial, comprising a pay-oil device associated with driving means fordrawing material therefrom, means for obtaining a continuous measure ofthe radius of a coil on the pay-oil device and means responsive to saidlatter means for initiating deceleration of the strip driving means at apredetermined rate, such that at the end of the deceleration period theend of the strip material has just left the pay-off device.

The invention further provides a method of controlling strip materialdrawn from a coil on a pay-ofl? device which comprises obtaining acontinuous measure of the size of the coil and using the measure toinitiate deceleration of the strip driving means at a predeterminedrate.

The radius of the coil can be measured by an arm and roller resting onthe coil or can be calculated from a measure of the rotational speed ofthe pay-01f device and the strip speed.

If the radius of the coil wound on the pay-olf device of radius r is r,then the annulus area of the strip is 1r(r lr If the length of the stripmaterial wound on the pay-off ice device is L and the thickness is h,then the annulus area is Lh.

..r- 1' T (A) If the linear strip speed is V and the deceleration rateis f, the deceleration time to zero strip speed is V/f at an averagespeed of V/ thus the length of strip leaving the coil from start ofdeceleration to zero speed is V /2f.

If at the completion of deceleration the end of the strip material hasjust left the pay-oil? device the length Lx of coil on the reel atinitiation of deceleration is Lx: V /2F.

Substituting this in Equation A, we get rx (B) where rx is the coilradius at which the deceleration should be initiated. If the strip speedV and the thickness h are known then rx can be calculated anddeceleration arranged to be initiated automatically when the coil radiusreaches rx.

One embodiment of apparatus for control of a strip pay-off device, inaccordance with the invention, will now be described by way of exampleonly, with reference to the accompanying diagrammatic drawing. A coil 12having an inner radius r and an outer radius r is mounted on a strippay-oif device 13. Strip from the pay-oif device passes between therolls 14 of a rolling mill driven by a motor M and onto a coiler 15. Thestrip is engaged by a billy roll 16 connected with a DC. tachometer 17which gives out a signal on line 18 proportional to the linear speed Vof the strip. A small roller 20 carried on an arm 21 is urged by aspring 22 into continuous contact with the outer surface of the coil 12the arm 21 is toothed and engages with a toothed wheel 23 which througharm 24, gears 25 and arm 26 operate a radius measuring potentiometer 27which emits a signal on line 28 proportional to the radius r. The signalon line 28 is fed to a squaring circuit 30 which emits a signalproportional to r on line 31 to a summing amplifier 32. The signal online 18 is fed to a squaring circuit 33 which emits a signal on line 34proportional to V this signal, together with a signal on line 35representing the predetermined deceleration f and a signal on line 36representing the strip thickness h are fed to a plurality of decadeswitches 37 from which is emitted on line 38 a signal proportional to -Vh/21rf; the latter signal is also fed to the summing amplifier 32 whichpasses a signal on line 39 proportional to to a level switch 40 alsoreceiving a signal on line 41 proportional to r the level switch 40 isarranged to emit a signal on line 42 when V h 2 2 7 21rf 7' signal online 42 passes via a mill stop relay 43 to the motor M to initiatedeceleration at the predetermined rate.

The coil radius r at any time is given by the relation V/21rN where N isthe rotational speed of the pay-ofi device, so that a measure of r mayalternatively be obtained by measuring V and N .and calculating r.

3 The value of It may alternatively be measured by a flying micrometer,an isotope gauge or calculated from the reduction in coil radius perrevolution of the pay-off device or a relationship between rate ofchange of coil diameter or pay-oil speed and strip speed.

We claim: 1. Apparatus for controlling strip material comprisa pay-offdevice for supporting a coil of strip, drive means for drawing stripfrom a coil on said payoff device, and control means for controllingsaid drive means comprising, size measuring means for continuouslyderiving an electrical signal proportional to the size of the coil onthe pay-off device, speed measuring means for continuously deriving anelectrical signal proportional to the linear speed of the stripmaterial, and deceleration means responsive to these signals forinitiating deceleration of said drive means at a predetermined rate andfor a predetermined period so that at the end of the deceleration periodthe end of the strip material is at a predetermined position relative tothe pay-T1 device. 2. In combination with apay-off device for supportinga coil of metallic strip material, a rolling mill having a pair of rollsfor drawing strip from the pay-off device and an electric motor forrotating said rolls, control means for controlling said motorcomprising;

size measuring means for continuously deriving an electrical signalproportional to the radius of a coil on said pay-off device, speedmeasuring means for continuously deriving an electrical signalproportional to the linear speed of the strip material, and decelerationmeans responsive to these signals 'for initiating deceleration of saidmotor at a predetermined rate and for a predetermined period such thatat the end of the deceleration period the end of the strip material hasjust left the pay-off device. 3. Apparatus for controlling stripmaterial comprising, a pay-off device for supporting a coil of strip,drive means for drawing strip from a coil on said payoif device andcontrol means for controlling said drive means comprising, sizemeasuring means for continuously deriving an electrical signalproportional to the square of the outer radius of the coil on thepay-ofi device (r speed measuring means for continuously deriving anelectrical signa1 proportional to the square of the linear speed of thestrip (v means for deriving an electrical signal proportional to apredetermined deceleration rate of the drive means (f),

means for deriving an electrical signal proportional to the thickness ofthe strip (h),

means arranged to receive said signals and combine said signals toobtain a further signal proportional to means for deriving an electricalsignal proportional to the square of the radius of the inner surface ofthe coil (r and means arranged to receive said further signal and saidsignal proportional to r and to compare said signals to initiatedeceleration of said drive means when References Cited UNITED STATESPATENTS 2,991,950 7/1961 Axon et a1 24255. 14 3,115,314 12/1963 Manleyet al 242--57 3,297,266 1/1967 Rumple 242-55.12 3,318,545 5/1967 Tobey24255.125 3,319,901 5/1967 Kurth 242-55.125

ANDRES H. NIELSEN, Primary Examiner.

US. Cl. X.R.

